Studies on Lactic Dehydrogenase Activity and Isozyme in Malignant Disease Part 2 Effects of Chemotherapy on Serum Lactic Dehydrogenase Activity and Isozyme of Tumor-Bearing Mice

Alterations of serum lactic dehydrogenase (S-LDH) activity and isozyme during therapy in tumor-bearing mice were assayed. 1. Normal Strong A mice receiving Mitomycin C (MMC), Chromomycin A(3) (TM), and Chloroquine phosphate (CQ) respectively were evaluated for S-LDH activity. S-LDH activities of the mice receiving MMC and TM were about twice as high as mormal, this seems to be the side effects of chemotherapeutic agents. The strong A mice receiving CQ showed no changes in S-LDH activity. 2. The strong A mice bearing Bashford carcinoma and the Swiss mice bearing fibrosarcoma were evaluated at weekly intervals for SLDH activity and isozymes. S-LDH activities gradually elevated for 4 weeks. In the Strong A mice bearing Bashford carcinoma LD(3) in creased and LD(1) decreased gradually. In the Swiss mice bearing fibrosarcoma LD(3) was higher than normal at every week. 3. S LDH activities in tumor-bearing mice undergoring therapy with MMC and TM, especially MMC, markedly decreased correlating with tumor regression. As to the S-LDH isozyme, LD(3) in mice receiving TM decreased correlating with decrease of S-LDH activity. In mice receiving others no characteristics were observed. 4. In couclusion, the assay of S-LDH activity and isozymes during therapy directing at tumors are useful in determining wheather or not a chemotherapentic agent affects the tumors.